Back in the early part of the 20th century, the term “killer shoes” had a whole different meaning. According to Invisible Paris, shoe-related illnesses and even deaths were quite common at the time, due to the aniline dyes used in shoe polishes and for dyeing leather black. There are some wonderful newspaper articles at the site with stories of shoe poisonings, and it finishes with this:
Although being poisoned by your shoes seems somewhat incredible today, aniline poisoning is something that still occurs, even if it is very rare. As the American Agency for Toxic Substances points out, this is perhaps because it has “a characteristic aromatic or fishy odor which provides adequate warning of acute exposure.” Beware then if you come across a pair of fishy-smelling shoes!
Yes, beware. Never trust a man who says, “Here, walk a mile in my (fishy-smelling) shoes!”